Fermentation stopped

[kproudfoot]

Recently made a Chocolate Cherry Stout. Started at 1052 and added White Labs WLP004 that I created a 2l starter 3 days before hand in a growler with foil. I had a nice yeast cake at the bottom. I cold crashed while brewing and decanted before pitching. Gravity got to 1030 and stopped (recipe said 1012). I talked to a friend who owns a brewery and he suggested aerating and adding dry yeast. I did that and saw a little action but only dropped to 1028. Any ideas what could have caused this? (More info/problem we had on brew day below).

1. When massaging temp rose to about 170, had a thermometer issue we didn’t catch. But OG still got to target

2. Has issues cooling (got to around 90 deg) so I put wort in my comical and was going to let it sit and cool for a few hours. However about an hour later I was praying the porcelain gods as the flu bug it. The next afternoon I took my yeast starter out of the fridge it had been cold crashing in for 24hrs and added it to my 70 deg wort.

3. I don’t use a fermentation chamber but my basement stays around 70 pretty consistently.

This is my 3 AG batch and second with a liquid yeast. The other worked fine.

Any insight would be greatly appreciated.

 

[ncbrewer]

I'd say 170* during the mash explains it (depending on timing). I've read about amalase enzyme that can help with this, but don't know anything about it. You might be able to google it and get some info.

 

[Calder]

What did you measure gravity with. If it was a refractometer, the FG reading needs converting. Refractometers are not accurate when alcohol is present.

 

[kproudfoot]

What did you measure gravity with. If it was a refractometer, the FG reading needs converting. Refractometers are not accurate when alcohol is present.

Refractometer during brew and hydrometer after.

 

[RM-MN]

Your mash temperature is most likely the culprit and you probably won't get the FG lower. High mash temperatures favor the alpha amalase enzyme because the high temperature denatures the beta amalase quickly which then leads to more dextrines, which are sugars that the yeast cannot digest. You can try swirling the yeast back into the beer and warming it but I think it is done.